The present invention is generally directed to materials and associated methods for the analysis and treatment of the effects and corresponding operation of invasive stimuli such as infection upon animal hosts, and in particular, is concerned with the identification of materials which may participate in the host response to such invasive stimuli.
Several common physiological and biochemical derangements have been observed in various mammalian hosts responding to a variety of invasive stimuli such as bacterial, viral, or protozoal infection; tumors; or endotoxemia; as well as in idiopathic states. For example, these responses include fever, leukocytosis, hyperlipidemia, reduced food intake (anorexia), reduced activity, wasting (cachexia), and other modifications in muscle, white blood cell and liver metabolism. In particular, recent studies aimed at elucidating the biochemical mechanism of cachexia in rabbits infected with Trypanosoma brucei noted that animals with a minimal parasite burden became moribund and exhibited an extreme hypertriglyceridemia, with a marked elevation of plasma very low density lipoprotein (VLDL). See C. A. Rouser and A. Cerami, MOL. BIOCHEM. PARASITOL. 1:31-38 (1980). The hyper-triglyceridemic state was remarkable in view of the severe wasting diathesis that accompanied this experimental infection. The elevation of plasma VLDL was shown to result from a clearing defect, caused by a loss of peripheral tissue lipoprotein lipase (LPL) activity.
Reduced LPL activity has been observed by others, and it has been noted that this condition has existed when the human body was in shock. See E. B. Man, et al., "The Lipids of Serum and Liver in Patients with Hepatic Diseases", CLIN. INVEST. 24 at 623, et seq. (1945); See also John I. Gallin, et al., "Serum Lipids in Infection", N. ENGL. J. MED. 281 at 1081-1086 (Nov. 13, 1969); D. Farstchi, et al., "Effects of Three Bacterial Infections on Serum Lipids of Rabbits", J. BACTERIOL. 95 at 1615, et seq. (1968); S. E. Grossberg, et al., "Hyperlipaemia Following Viral Infection in the Chicken Embryo: A New Syndrome", NATURE (London) 208 at 954, et seq. (1965); Robert L. Hirsch, et al., "Hyperlipidemia, Fatty Liver and Bromsulfophthalein Retention in Rabbits Injected Intravenously with Bacterial Endotoxin", J. LIPID. RES. at 563-568 (1964); and Osamu Sakaguchi, et al., "Alternations of Lipid Metabolism in Mice Injected With Endotoxins", MICROBIOL. IMMUNOL. 23 (2) at 71-85 (1979); R. F. Kampschmidt, "The Activity of Partially Purified Leukocytic Endogenous Mediator in Endotoxin Resistant C3H/HeJ Mice", J. LAB. CLIN. MED. 95 at 616, et seq. (1980); and Ralph F. Kampschmidt, "Leukocytic Endogenous Mediator", J. RET. SOC. 23 (4) at 287-297 (1978).
Additionally, publications are known by the Applicants that discuss the identification and existence of "mediators" that appear to be involved in the host response to infection; and in particular, the following articles, the texts of which are incorporated herein by reference, are listed: Sipe, J. D., et al., J. EXP. MED., 150:597-606 (1979); and Barney, C. C., et al., LIPTON, J. M. (Ed.), FEVER: INTERNATIONAL SYMPOSIUM, Dallas, Texas, Apr. 11-12, 1979 XII+263P. Raven Press: New York, Illus. ISBN 0-89004-451-1 (08877), 0 (0), pp.111-122 (1980); and Dinarello, C. A., "Human Leukocytic Pyrogen: Purification and Development of a Radioimmunoassay", PROC. NATL. ACAD. SCI. USA, 74(10) at 4624-4627 (October, 1977). All of the factors identified and investigated by each of the authors in the above noted articles and the articles authored or co-authored by Kampschmidt have been determined to comprise a single grouping of factors which has been identified as interleukin-1 (IL-1). This determination has been documented in an article by Charles A. Dinarello, published in REVIEWS OF INFECTIOUS DISEASES, at Volume 6, No. 1 (January-February, 1984), the text of which is also incorporated herein by reference.
A similar deficiency of LPL activity was noted by Applicants in C3H/HeN mice after administration of Escherichia coli lipopolysaccharide (LPS). In contrast, the loss of LPL activity was not demonstrable in C3H/HeJ mice, which are genetically resistant to LPS. This resistance to endotoxin-induced LPL deficiency could be circumvented by the administration of serum obtained from endotoxin-sensitive animals that had been injected with LPS two hours previously. Similarly, resistance could be overcome by injecting conditioned medium from endotoxin-stimulated thioglycollate-elicited peritoneal macrophages, obtained from sensitive mice. These findings were set forth in full detail in Application Ser. No. 414,098, now U.S. Pat. No. 4,603,106, the disclosure of which is incorporated herein by reference.
The above work was prompted by the belief that the "mediator" or "mediators" existed and were suspected to have a significant effect upon general anabolic activity of energy storage cells in the animal host. It was suspected that such "mediator" exerted a depressive effect upon the activity of certain anabolic enzymes, whose reduced activity was observed for instance, where the hosts enter the condition known as shock, as in response to infectious invasion. Resultingly, the relationship of the mediator produced by endotoxin-stimulated peritoneal mouse exudate cells, upon endotoxin-sensitive and endotoxin-insensitive mice alike, and the development through such investigation of a reagent for the measurement of anabolic enzyme activity was set forth in first filed abandoned application Ser. No. 299,932, incorporated herein by reference.
Further investigation of this system was made in conjunction with the 3T3-L1 "preadipocyte" model system, and the corresponding development of methods and associated materials for the development of antibodies to the "mediator" and other diagnostic procedures was then set forth in application Ser. No. 351,290, also incorporated herein by reference and now abandoned. Thereafter, in subsequent application Ser. No. 414,098, now U.S. Pat. No. 4,603,106, it was established that the mediator substance derived from the endotoxin stimulation of macrophage cells exhibited the activities of suppressing the anabolic enzymes lipoprotein lipase, acetyl Coenzyme A Carboxylase and fatty acid synthetase, and further, inhibited the growth and differentiation of erythroid-committed cells.
Additional work set forth in articles (1) and (4) by Beutler et al., and Application Ser. No. 766,852, the disclosure of which is incorporated herein by reference, has resulted in the discovery that the earlier identified mediator substance contained a further protein component which possesses a number of activities, which distinguished it from both the mediator substance and the other factors identified in the art and known as interleukin-1 and interleukin-2. Further work set forth in articles (7)-(9) and patent application Ser. No. 104,827, the disclosure of which is incorporated herein by reference, established the presence of an additional factor (MIP-1) in the mediator substance which factor demonstrates a distinguishable profile of activities.
Subsequently, the present inflammatory cytokine MIP-2 was isolated and purified and its distinctive activities elucidated as set forth in immediate patent application Ser. No. 240,078 now abandoned. Since that time, the complete sequence of the present cytokine has been determined following the cloning of its cDNA, and expression of the cytokine has been pursued. The present application is intended to include the additional information regarding this cytokine that is now available as a result of the investigations of the inventors herein.
MIP-2 is a member of a homologous multigene family. Members of this family that have highest homology in protein sequence (generally predicted from cloned cDNA) include MGSA and KC. MGSA (Richmond et al., EMBO J. 7:2025 (1988) is an autocrine growth factor with potent mitogenic activity secreted by human melanoma cells and is the product of the human gro gene (Anisowicz et al., PROC. NAT. ACAD. SCI. USA 84:7188 (1987). MGSA has 61.6% identity in amino acid sequence to MIP-2; the predicted protein sequence of the hamster homolog of MGSA has 68.4% identify to MIP-2. The murine KC gene product is induced by PDGF and is thought to be the murine homolog of the human MGSA/gro gene (66.3% amino acid identity to MIP-2).
The present applicants know of no prior art on the expression of recombinant MIP-2 although Lipes et al., (PROC. NATL. ACAD. USA 85:9704, 1988) described baculovirus expression of Act-2 cDNA, a putative human homolog of murine MIP-1.beta., to show that the protein encoded was secreted and to identify the mature N-terminal sequence.
Members of the MIP-1 and MIP-2 gene families have been expressed but the pertinence of these results to MIP-2 expression is questionable. The literature is summarized as follows. JE, a cDNA that encodes a protein with homology to MIP-1.alpha. and MIP-1.beta., has been expressed in COS-1 cells to confirm that it encodes a polypeptide core of about 12 kDa (Rollins et al., PROC. NATL. ACAD. SCI. USA 85:3738, 1988). KC, a cDNA that encodes a protein with homology to MIP-2, has been expressed in COS-1 cells to show that it encodes a secreted protein by Oguendo et al., J. BIOL. CHEM. 264:4133 (1989). Connective tissue activating peptide-III (CTAP) reported by Mullenbach et al., J. BIOL. CHEM. 261:719 (1986) and IP-10, reported by Luster and Ravetch, J. EXP. MED. 166:1084 (1987) both members of the MIP-2 gene family, have been expressed as an .alpha.-factor fusion in yeast and in E. coli., respectively. Finally, Lindley et al., PROC. NAT. ACAD. SCI. USA 85:9199 (1985) have expressed NAF, a member of the MIP-2 family, in E. coli. After purification and renaturation, this recombinant protein was found to have the same bioactivity identified for the native molecule.